The presence of vapors, and their concentration in air, is monitored in many fields of endeavor. Various methods for detecting vapors (e.g., volatile organic compounds (VOCs)) have been developed including, for example, photoionization, gas chromatography, gravimetric techniques, spectroscopic techniques (e.g., mass spectrometry, infrared spectroscopy, or fluorescence spectroscopy), and absorptive sensing techniques.
In capacitance sensors, the capacitance of two conductive electrodes (typically parallel or interdigitated), varies as the dielectric constant of material between the two electrodes changes due to the presence of an environmental analyte vapor. Conventional capacitance sensors can be inexpensive to manufacture, but may lack the sensitivity of other more costly techniques.
There is a need for capacitance sensors with improved sensitivity to analyte vapors.